Packaging film having permeable patch covering an opening in the film and package made therefrom

ABSTRACT

A package, which allows for butchering and packaging of fresh red meat at a centralized facility is provided which includes an impermeable tray supporting the product, a first film sealed to the tray for enclosing the product, a channel defined within the first film for exchanging gases into and out of the package, and a second impermeable film enclosing the first film, such that removal of the impermeable film provides for the exchange of gases into and out of the package. The channel for exchanging of gases may be perforations defined within the first film, a second highly permeable film sealed to the first film, or an enlarged opening formed within the first film, which is enclosed with a patch following adequate gas exchange at retail. Such gas exchange is required to release any low oxygen atmosphere and allow for the introduction of oxygen to the packaged meat product. The channel for exchanging gases having a gas transmission rate of at least about 50,000 cc/m 2 /24 hrs./atm. at 73° F.

BACKGROUND OF THE INVENTION

This application is a continuation of application Ser. No. 08/828,903,filed Apr. 2, 1997 and now U.S. Pat. No. 6,667,067, which is a divisionof application Ser. No. 08/471,065, filed Jun. 6, 1995 and now U.S. Pat.No. 5,686,126.

The present invention relates generally to packages for fresh red meat.Particularly, this invention is directed to the packaging of foodproducts such that the packaged product may be maintained in onecondition under certain circumstances and then converted to anothercondition. Specifically, packages in accordance with the presentinvention provide for distribution of a packaged product in a low oxygenenvironment and for introduction of oxygen to the product surface at asupermarket or other retail outlet. Such introduction of oxygen isachieved either by permeation of oxygen through a film in contact withthe product surface or through an exchange of atmospheric oxygen with alow oxygen gaseous atmosphere contained around the product.

While a wide variety of food products can be packaged in accordance withthe teachings of this invention, it is particularly advantageous inconnection with the packaging of fresh red meat such that the meat maybe transported in a low oxygen atmosphere, that is, preferably 0.5% O₂or less, most preferably 0.05% O₂ or less, and then caused to bloom whenit reaches a supermarket by exposure to oxygen.

Historically, large sub-primal cuts of meat have been butchered andpackaged in each supermarket. This, however, can be inefficient andresult in certain undesirable additional costs. For example, all cutsfrom a large sub-primal must be sold at once. Instead it would bepreferable to permit the meat to be butchered and packaged at a centralfacility which benefits from economies of scale and thereafter shippedto individual supermarkets such as is done, for example, with manypoultry products.

In the past, the goal of central fresh red meat processing has not beenachievable because most consumers prefer to buy meat which is reddenedin color as a result of exposure to oxygen. However, the meat maintainsits reddened color for approximately one to three days and, thereafter,turns a brown color which is undesirable to most consumers.

Therefore, if the meat was butchered and packaged in a gas permeable(hereinafter “permeable”) film, as is typical at retail, at a centrallocation and then shipped to another location for eventual sale, in alllikelihood, by the time the package reached the retail outlet the meatwould have undergone the transformation to the brown color and would beeffectively unsalable. Conversely, if the meat was butchered andpackaged at a central location in a gas-impermeable (hereinafter“impermeable”) film, either under vacuum or with vacuum and a low oxygengas flush, and then shipped to another location for eventual sale, themeat would reach the retail outlet having a purple color which istypical of meat prior to exposure to oxygen. Heretofore, marketingefforts to teach the consumer about the harmlessness of the purple colorhave proved to be difficult. And, if the gas impermeable film was acomponent of a conventional package having a tray which is overwrappedor lidded with a film and which contains a low oxygen atmosphere, theimpermeable film would have to be removed and replaced with a permeablefilm in order to allow for bloom of the meat to a bright red color priorto display for the consumer, negating to a large extent the benefits ofa central processing facility.

A variety of packages have been developed in an effort to provide ameans for transporting meat in a low oxygen environment and for quicklyand easily introducing oxygen to the meat at the retail outletimmediately prior to display to the consumer.

One approach to solving this problem has involved the development ofpeelable films. That is, films have been developed which readilydelaminate into permeable and impermeable portions. Such a film issealed to a support member, such as a tray, which contains the meatproduct, thereby forming a gas impermeable package for distribution. Atthe retail outlet, the gas impermeable portions are peeled from the filmleaving a permeable film sealed to the tray and, therefore, a gaspermeable package which allows the meat to bloom to bright red becauseof the exchange with atmospheric oxygen.

The peelable film may extend over the contained product and be sealed tothe periphery of the tray as a lid or it may be heated and draped overthe product under vacuum to form to a vacuum skin package. However, forboth types of packages the principal drawback is the relatively low gastransmission rate of the permeable film portion after removal of theimpermeable portion. That is, although the permeable portion of thepeelable film has a much higher gas transmission rate than that of theentire film prior to delamination, 5,000 to 25,000 cc/m²/24 hrs./atm. at73° F. a compared to 0 to 50 cc/m²/24 hrs./atm. at 73° F. prior todelamination, it is still too low to effect bloom of the packaged meatin a low oxygen gaseous atmosphere in a short period of time, except inareas of intimate permeable film to meat contact.

Most of the other approaches to achieving the goal of central fresh redmeat processing have involved the development of a variety of dual webpackages of the type having a permeable film covering the meat productand an impermeable film, which is removed at the retail outlet, coveringthe permeable film wherein the permeable film and the impermeable filmare separate, discreet films.

Examples of these types of packages include dual overwrap packageswherein a permeable film is wrapped around the meat and its supportmember and an impermeable film is wrapped about the permeable film; duallid packages which include a permeable lid and an impermeable lid sealedto the periphery of the support member; and packages with a head spacewhich allows for the introduction of a treating gas, typically nitrogen,carbon dioxide or some mixture of the two, between a permeable filmadjacent to the meat product and an impermeable upper web. But, as isthe case with the peelable films discussed above, each of these dual webpackages are limited in their effectiveness by the permeability of thepermeable film. Typical gas transmission rates for commercially viablegas permeable films are 5,000 to 25,000 cc/m²/24 hrs./atm. at 73° F.which is too low to effect rapid red meat bloom by exchange of the lowoxygen gas and/or gases out and the atmospheric oxygen in.

A further package developed to allow for central fresh red meatprocessing includes a gas impermeable upper lid with a valve defined inthe lid. The package may include a treating gas between the packagedmeat and the upper lid during distribution which is withdrawn throughthe valve and replaced with an oxygen-rich gas. Although a rapid bloomis possible with this system, it has the disadvantages of requiringtrained operators at the retail outlet and relatively expensiveequipment to exchange each package thus negating the cost savings of acentral processing facility. The presence of the valve has the furtherdisadvantage of creating a package appearance which is different fromthat which consumers are accustomed to seeing for meat packaging.Further, a gas space between the meat product and the impermeable filmis required to maintain a bloomed color which yields an underfilledpackage appearance.

Yet another package developed to allow for central fresh red meatprocessing provides for an excellent exchange of gases and rapidintroduction of oxygen in which an upper impermeable web covers a lowerpermeable web which includes unsealed areas in the seal of the permeableweb to the tray. However, the intermittent sealed and nonsealed areasare formed by an altered sealing head which comprises a series ofsealing “fingers” rather than a conventional, continuous sealingsurface.

Thus, it is an object of the present invention to provide a packagewhich allows for central processing of fresh red meat with minimalprocessing required at retail.

It is yet another object of the present invention to provide a packagewhich is similar in appearance to that which consumers are accustomed toseeing for meat packaging.

It is a further object of the present invention to provide a packagewhich allows for rapid bloom of fresh red meat.

It is yet another object of the present invention to provide a packagewhich may be assembled, filled and sealed at a central processingfacility on conventional equipment.

SUMMARY OF THE INVENTION

These as well as other objects are achieved by providing a package for aproduct which includes a product, an impermeable support membersupporting the product, a first film sealed to the support member forenclosing the product, means defined within the first film forexchanging gases into and out of the package, such means for exchanginggases having a gas transmission rate of at least about 50,000 cc/m²/24hrs./atm. at 73° F., and a second impermeable film enclosing the firstfilm and the means defined therein for exchanging gases, such thatremoval of the second impermeable film provides for the exchange ofgases into and out of the package.

Such objects are further achieved by providing a package for a productwhich includes a product, an impermeable support member supporting theproduct, a multilayer web sealed to the support member for enclosing theproduct, the multilayer web being delaminatable into a permeable portionand an impermeable portion with the permeable portion being directlyadjacent and sealed to the support member and the impermeable portion,whereby the permeable portion remains sealed to the support member upondelamination of the impermeable portion therefrom, and wherebydelamination of the impermeable portion from the permeable portiondefines at least one channel within the permeable portion allowing for afree flow of gases through the at least one channel, into and out of thepackage.

Such objects are also achieved by providing a package for a productwhich includes a product, a support member supporting the product, afirst film sealed to the support member for enclosing the product, asecond, impermeable film for enclosing the first film, at least onechannel defined within the first film and enclosed by the second,impermeable film whereby removal of the second, impermeable film allowsfor a free flow of gases through the at least one channel, into and outof said package, and a patch for enclosing the channel after the gasesflowing into and out of the package have achieved a desired equilibrium.

Such objects are further achieved by providing a package for a productwhich includes a product, a support member supporting the product, afirst film sealed to the support member, a second film sealed to thefirst film, the second film having a gas transmission rate of at leastabout 50,000 cc/m²/24 hrs./atm. at 73° F., the product being enclosedwithin the support member by the first and second films, a third,impermeable film for enclosing the first and second films, wherebyremoval of the third, impermeable film allows for a free flow of gasesthrough the second film, into and out of the package.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of preferred embodiments of the inventionfollows, with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a package, according to the invention;

FIG. 2 is a partial cross-sectional view of the package of FIG. 1;

FIG. 3 is a partial cross-sectional view of another package inaccordance with the present invention;

FIG. 4 is a partial cross-sectional view of yet another package inaccordance with the present invention;

FIG. 5 is a perspective view of a further package in accordance with thepresent invention;

FIG. 6 is a cross-sectional view of the package of FIG. 5;

FIG. 6A is a cross-sectional view of the package of FIG. 5 followingremoval of the impermeable web and application of the patch;

FIG. 7 is a perspective view of a still further package in accordancewith the present invention;

FIG. 8 is a cross-sectional view of the package of FIG. 7; and

FIG. 9 is a cross-sectional view a further embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a tray-type package suitable forthe central processing of fresh red meat which includes a gasimpermeable (hereinafter “impermeable”) support member or tray, a firstfilm sealed to the tray which includes a means defined therein forproviding for an exchange of gases into and out of the package, and animpermeable film which encloses the first film and means for exchanginggases defined therein. The package most preferably contains a low oxygengaseous atmosphere such as, for example, a nitrogen/carbon dioxide mix.Thus, removal of the impermeable film allows for a release of the lowoxygen atmosphere and for introduction of oxygen to the packaged meatproduct.

The means for exchanging gases defined within the first film may beperforations defined within the first film which are exposed uponremoval of the impermeable film, an enlarged opening defined within thefirst film which is exposed upon removal of the impermeable film and iscovered with a patch or label following a period of time adequate forsufficient exchange of gases, or a highly permeable film, sealed to thefirst film, which provides an area of exceptionally high gastransmission upon removal of the impermeable film.

Looking to the first group of packages, FIGS. 1 through 4 illustratepackages having a variety of multilayer webs which may be delaminatedinto impermeable upper webs and perforated lower webs. Such multilayerwebs allow for a simplified packaging operation employing conventionalsingle flange trays, a vacuum or, preferably, a vacuum and gas flushwith a low oxygen atmosphere, and sealing of a single web to the trayflange in a single sealing step. At retail, the upper layer of the webis peeled away revealing a perforated lower layer which has a gastransmission rate of at least about 50,000 cc/m²/24 hrs./atm. at 73° F.,allowing for a rapid release of the low oxygen atmosphere andintroduction of oxygen for immediate blooming of the packaged meatproduct. Following blooming, the package may optionally be overwrappedwith a gas permeable film such as is employed in conventional retailoverwrapping to act as a dust cover for the packaged meat product.

Looking to FIG. 1, a package 10 in accordance with the present inventionincludes a support member or tray 12 having side walls 14 and a base 16defining an inner cavity 18 for receiving product 20. A peripheralflange 22 is defined about the upper portions of side walls 14.Multilayer web 26 is sealed to the tray at the flange 22.

FIG. 2 is a cross-sectional view of the package 10 of FIG. 1 includingtray 12 with web 26 sealed to flange 22. For the present embodiment, web26 is a single, coextruded multilayer film which may be delaminated intoimpermeable and permeable portions. Films which may be so delaminatedare well known in the art and are formed by coextruding a multilayerfilm which includes two layers immediately adjacent to each other andwhich demonstrate a weak force of adhesion therebetween. Preferred bondstrength equate to peel forces to separate these adjacent layers of fromabout 0.02 to about 0.05 lbs. Thus, web 26 delaminates into an upperimpermeable portion 28 and a lower permeable portion 30, as is shown.

Web 26 has defined therein partial perforations 32 which extend throughthe permeable portion of the film. Upon delamination it is seen that theimpermeable portion 28 is substantially free of such perforations.Accordingly, when partially perforating a film or web for use in thepresent inventive package it is necessary to know the extent andthickness of the permeable and impermeable layers contained therein andfor the perforations to extend through the permeable layers but not, toany material extent, through the impermeable layers. That is, theperforations may extend partially, to a slight degree, into theimpermeable layers but may not interfere with the gas barrier propertiesof the impermeable portion of the multilayer film. Also included areperforations which extend substantially but not necessarily completelythrough the permeable portion, commonly referred to as blindperforations.

Thus, when impermeable portion 28 is peeled away, perforations 32defined within the remaining permeable portion 30 allow for a rapidexchange of gases and consequent blooming of the packaged meat product,as is shown. It should be noted that web 26 is a multilayer film whichdelaminates into permeable and impermeable portions to uncover thepermeable portion and enhance the flow of gases into and out of thepackage. It is also within the scope of the present invention, althoughless preferred, to provide a multilayer film which delaminates into twoimpermeable portions, one that is directly sealed to the support memberhaving perforations. Such alternative is less preferred because theinherent permeability of a permeable film portion also aids in gasexchange. More importantly, in areas of intimate film to meat contact animpermeable perforated film portion will preclude bloom of the meatexcept in the specific areas of perforation, thus resulting in anon-bloomed area containing dotted areas of bloom. And, because of theexpense involved in coextruding two gas barrier layers in a singlemultilayer film when one will merely be perforated to render itpermeable-anyway, it is generally preferred that the perforated portionis permeable.

FIG. 3 is directed to a package 50 which is similar in operation butsomewhat different in manufacture from that of package 10 of FIGS. 1 and2, above, Hereagain package 50 includes tray 52 having side walls 54 anda base, not shown, which defines a cavity 58 for receiving a product. Aperipheral flange 62 is defined about the upper portions of side walls54. Multilayer web 66 is sealed to the tray at flange 62. For thepresent embodiment, web 66 is a coextruded, multilayer film or laminateof a nonperforated impermeable film 68 and a film 70 which includesperforations 72 defined therein. As with the single film embodimentdiscussed above, it is preferred that film 70 is a permeable filmbecause, although the perforations defined therethrough greatly increasethe gas transmission rate of the film, such inherent permeability aidsin gas exchange and blooming will be hindered in areas of intimate filmto meat contact. However, a nonpermeable film which is perforated torender it permeable is also within the scope of the present invention.As is shown in FIG. 3, nonperforated film 68 is peeled away to revealperforated film 70 for a rapid exchange of gases and blooming of thepackaged meat at retail.

FIG. 4 illustrates yet another package 100 in accordance with thepresent invention which includes a support member or tray 112 havingside walls 114 and a base defining an inner cavity 118 for receivingproduct. A peripheral flange 122 is defined about the upper portions ofside walls 114. Multilayer web 126 is sealed to the tray at the flange122. For the present embodiment, web 126 is a laminate of impermeablefilm 128 and multilayer film 130 having perforations 132 definedtherein. Hereagain, multilayer film 130 is capable of delaminating intotwo separate film portions. However, for purposes of the presentembodiment it is necessary that the force require to delaminate film 130into two separate film portions is less than the force required todelaminate impermeable film 128 from the upper surface of multilayerfilm 130. That is, film 130 is formed by coextrusion, is perforated, andis then laminated to impermeable film 128. However, unlike laminate 66above, impermeable film 128 may not be readily peeled from film 130.Rather, the bond strength between film 128 and multilayer film 130 isgreater than the interlayer strength of film 130 such that any attemptto remove film 128 results in the cohesive failure and interlayerdelamination of film 130 into two separate film portions. Thus, upperportion 136 remains bonded to impermeable film 128 and lower portion 138remains sealed to tray flange 122.

As with the webs discussed with respect to the embodiments set forthabove, the permeability of film 130 prior to its perforation is somewhatoptional and may encompass a variety of combinations. Most preferablymultilayer film 130 is a permeable multilayer film which is perforated,laminated to impermeable film 128 and, upon any attempt at removal offilm 128, delaminates into two film portions, one of which remainsbonded to film 128 and the other of which remains sealed to tray 112enclosing the packaged meat product. Therefore, it should be understoodthat FIG. 4 illustrates the separation of portions 136 and 138 as shownbut that film 130 being multilayer can be substantially separable rightat the layer-layer interface as well. However, it is also within thescope of the present invention to provide a multilayer impermeable filmwhich delaminates into permeable and impermeable portions. Suchmultilayer film is perforated, laminated to impermeable film 128,preferably with the impermeable portion being immediately adjacent toimpermeable film 128 and the permeable portion being sealed to tray 112,and, upon any attempt at removal of film 128, delaminates into two filmportions, the impermeable portion remaining bonded to film 128 and thepermeable portion remaining sealed to tray 112. Because the film 130 isperforated all the way through it is also within the scope of theinvention, although less preferred, to laminate film 130 to impermeablefilm 128 with the permeable portion being immediately adjacent to film128 and the impermeable portion being sealed to tray 112. Similarly, itis also within the scope of the present invention to employ a multilayerfilm which delaminates into two impermeable portions such that the filmportion which remains sealed to tray 112 upon removal of film 128 is aperforated impermeable film, which is, of course, rendered permeable byits perforations. As above, it is preferred that the remaining filmportion 138 is permeable because, although the perforations definedtherethrough greatly increase the gas transmission rate of the film,such inherent permeability aids in gas exchange and because of potentialpreclusion of bloom in areas of intimate film to meat contact.

Turning now to other means for exchanging gases which may be definedwithin the first film of the present invention, FIG. 5 illustrates apackage 150 which includes a tray 152 having side walls 154 and a base156 defining a cavity 158 for receiving a product 160. As will bediscussed in greater detail below, for purposes of the presentembodiment, it is preferred that a dual flange 162 is employed whichincludes outer flange portion 164 and inner flange portion 166 which areseparated by depression 168.

As is shown better in the cross-sectional view of FIG. 6, a first film170 is sealed to inner flange portion 166 and includes an enlargedopening 172 defined therein. The opening 172 is of sufficient dimensionsto impart of gas transmission rate of at least 50,000 cc/m²/24 hrs./atm.at 73° F., and more preferably at least about 75,000 cc/m²/24 hrs./atm.at 73° F., to the film. For purposes of the present embodiment it ispreferred that film 170 is comprised of a gas permeable film, as will beshown below.

Impermeable film 174 encloses film 170 and opening 172 defined thereinand is sealed to outer flange portion 164. Preferably, the seal formedbetween film 174 and outer flange portion 164 is such that film 174 maybe easily peeled away at retail. Thus, upon removal of impermeable film174, the enlarged opening 172 defined in film 170 allows for a rapidexchange of gases out of and into the package and a concurrent bloomingof the packaged meat product. Following such gas exchange opening 172 isenclosed with a patch 176 as is shown in FIG. 6A. Alternately, opening172 can be formed subsequent to removal of film 174 and patch 176 thenapplied. Such patch may be permeable or impermeable. Generally, it ispreferred that either film 170 or patch 176 or both are permeable toallow for a continued gas exchange during retail display. Also, a singleimpermeable web having a patch covering the hole is within the scope ofthe invention. If film 170 is gas impermeable, then the patch 176preferably comprises a permeable material. However, since the opening172 and its patch 176 define only a relatively small percent of thesurface area of film 170, a preferred option is for film 170 to bepermeable. Then patch 176 may be either permeable or impermeable, butneed not serve as the sole means of gas exchange during retail display.Furthermore, rather than giving the appearance that something went wrongand the package was “patched up” for retail display, it is preferredthat the patch serve as all or a portion of a label identifying theproduct.

Although a single enlarged opening is illustrated, two or more smalleropenings may also be employed so long as they impart sufficient gas fluxcapability to the film. However, it is generally preferred that multipleopenings be grouped together such that they may be enclosed by a singlepatch or label.

FIG. 7 illustrates yet a further embodiment of the present invention inwhich a package 200 includes a tray 212 with side walls 214 and a base216 defining a cavity 218 for receiving a product 220. For purposes ofthe present embodiment it is preferred that a dual flange 222 isemployed which includes outer flange portion 224, inner flange portion226 and depression 228 separating the two.

As is better shown in the cross-sectional view of FIG. 8, a first film230 encloses the product and is sealed to the tray 212 at inner flangeportion 226. An enlarged opening 232 is defined within the first filmand a second film or patch 234 is sealed to the first film enclosingopening 232. For all the embodiments of a permeable patch or a filmcovering a hole in a first film, the patch/film permeable material cancomprise any permeable polymeric material compatible with the web it issealed to. It can comprise, for example, polyethylene or any of avariety of ethylene copolymers including, for example, ethylene vinylacetate, ethylene acrylate copolymers, ethylene acrylic acid copolymersincluding metal neutralized salts thereof, and ethylene alpha-olefincopolymers. Most preferred is a patch/film exhibiting a gas transmissionrate of at least about 50,000 cc/m²/24 hrs./atm. at 73° F., morepreferably at least about 75,000 cc/m²/24 hrs./atm. at 73° F. Examplesof such include spun-bonded polyolefin or polyester materials, such asTyvek manufactured by DuPont and other microporous materials which arewell known in the art. Impermeable film 236 encloses the first film 230and patch 234 and is sealed to the outer flange portion 224 of tray 212.Preferably, the seal between impermeable film 236 and outer flangeportion 224 is such that film 236 may be peeled away from the packageleaving first film 230 and patch 234 enclosing the product. Theexceptionally high gas transmissibility of patch 234 provides for arapid exchange of gases and blooming of the package meat product.Although it is preferred that film 230 is permeable, an impermeable filmmay be employed so long as the enlarged opening and highly permeablepatch are sufficiently large to allow for a free flow of gases into andout of the package.

Thus package 200 is formed by sealing a first film 230 to inner flangeportion 226 of tray 212 which contains product 220 therein. An enlargedopening is formed and is covered with the highly permeable second filmor patch 234. Impermeable film 236 is then sealed to outer flangeportion 224. Optionally, enlarged opening 232 may be formed prior to theapplication and sealing of film 230 to the tray. If such is the case,second film or patch 234 may also be sealed to the first film 230 priorto its application and sealing to tray 212.

An inventive package which is similar in operation but different inappearance and manufacture is illustrated in FIG. 9. Package 250includes tray 252 which has side walls 254 and base 256 defining cavity258 for receiving product 260. Dual flange 262 includes outer flangeportion 264 and inner flange portion 266 separated by depression 268. Afirst film 270 is sealed to inner flange portion 266. A second film 272,preferably a continuous strip, is sealed to first film 270. As with thepatch/film, discussed above, the present second film 272 is preferablycomprised of a permeable material as described above, such as Tyvek.Impermeable film 274 encloses the first and second films and is sealedto tray 252 at outer flange portion 264. Impermeable film 274 may bepeelably removed to expose the first and second films. The highlypermeable nature of second film 272 provides for a rapid exchange ofgases out of and into the package and an immediate bloom of the packagedmeat product.

Preferably, a series of perforations or slits 275 is introduced intofilm 270 underlying film 272, preferably after film 272 is sealedthereto, to augment the free flow of gases into and out of the package.Rather than being applied as a patch, the second film 272 of the presentembodiment is preferably sealed to the first film prior to applicationand sealing of the first film to the tray.

For all embodiments of the present invention it should be generallynoted that dual flange trays are preferred whenever two separate websmust be sealed to a single tray. However, a conventional, single flangetray may be employed when a precise means is available for sealing thefirst film to an inner portion of the single flange and for subsequentlysealing the impermeable film to an outer portion of the single flange.That is, the primary reason a dual flange is preferred for use as thetray of the present invention is that it facilities the automatedsealing of two separate webs to the flange. A second circumstance underwhich a single flange may be employed as the tray for dual-webembodiments of the present inventive package is when an adequate,peelable seal may be made between the impermeable film and the firstfilm. Rather than sealing the impermeable film directly to the tray, itis possible, with the proper selection of film components, to form aseal directly to the first film which may be peeled away withoutdisturbing the seal between the first film and the tray flange.

The permeable film or web of the present invention is an oxygenpermeable or non-barrier film or skin which may be a formable orstretchable material. Typical polymeric materials for the presentpermeable film may include any material which may be securely sealed andbonded to the support member, such as polyethylene or any of a varietyof ethylene copolymers including, for example, ethylene vinyl acetate,ethylene acrylate copolymers, ethylene acrylic acid copolymers includingmetal neutralized salts thereof, and ethylene alpha-olefin copolymers.Such ethylene alpha-olefins may be heterogeneous or homogeneous innature. That is, ethylene alpha-olefins which have been formed byconventional Zeigler-Natta catalysis and are heterogeneous in nature,such as linear low density polyethylene (LLDPE), are within the scope ofthe present invention as well as such copolymers which are formed bysingle site catalysis, such as any of a variety of forms of metallocenecatalyst technology, and are homogeneous in nature are also within thescope of the present invention. A preferred permeable film for use inaccordance with the present invention is a symmetrical, five layeroriented film having the structure:EVA/LLDPE/EVA/LLDPE/EVAalthough a wide variety of permeable films may be employed.

The impermeable film or web of the present invention may be any suitablebarrier layer, film or laminate which is substantially impermeable togas such as oxygen so that a fresh meat product contained in a vacuum orother low oxygen atmosphere possesses an enhanced shelf life over apackage without the barrier layer. Suitable polymeric materials havinggas barrier properties for use in the present invention include ethylenevinyl alcohol copolymers, vinylidene chloride copolymers (PVDC) such asvinylidene chloride vinyl chloride or vinylidene chloride methylacrylate. Laminates of a sealable film and a barrier structure whichincludes a barrier layer and a tough, non-forming material such as abiaxially oriented nylon or biaxially oriented polyester are especiallypreferred for use as the impermeable lidding of the present inventivepackages. A preferred impermeable web has the structure:biax nylon/PVDC//EVA/LLDPE/sealwherein the double slashes (//) indicate adhesive lamination of the twowebs, although a variety of laminates and multilayer films may beemployed as the impermeable web of the present invention.

Generally, the films or webs which may be employed in accordance withthe present invention may be monolayer or multilayer. Multilayer filmsmay be employed when all of the properties required of the film cannotbe achieved by a single polymeric component or a blend of polymers in asingle layer. For example, an impermeable film to be sealed to a tray inall likelihood will comprise a multilayer film because severalproperties are needed including peelable sealability, oxygen barrier andimpact properties, and outer abuse properties. Thus, the film employedwill most likely contain three layers at a minimum: a seal layer, abarrier layer and an outer abuse layer. Further internal layers such asadhesive layers and bulk layers may also be included. Laminates ofsealable films and nonforming materials such as biaxially orientedpolyester or biaxially oriented nylon are also within the scope of thepresent invention and are widely recognized as superior lidstocks fortray-type packages.

For all embodiments, the tray must be impermeable, but may be chosenfrom a variety of commercially available designs and compositions. Thatis, the tray may be formed of a rigid solid polymer, a barrier sealantcoated polymer, a barrier sealant coated foamed polymer, or a barriersealant coated pulp or paperboard tray. If foamed, a barrier film mustbe included, at least, on the inner surface of the tray in order toprevent outgassing of residual gases into the package.

Generally, the films employed in the present invention may be multilayeror monolayer, although, of course, those films defined as delaminatable,multilayer films must include at least two layers. Typically, the filmsemployed will have two or more layers in order to incorporate a varietyof properties, such as, for example, sealability, gas impermeability andtoughness, into a single film.

The foregoing description of preferred embodiments of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed, and modifications and variations are possible in light of theabove teachings or may be acquired from practice of the invention. Theembodiments were chosen and described in order to explain the principlesof the invention and its practical application to enable one skilled inthe art to utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. It isintended that the scope of the invention be defined by the claimsappended hereto, and their equivalents.

1. A package for a product, comprising: a product; a support membersupporting the product; a first, substantially gas-impermeable filmsealed to said support member to enclose the product between saidsupport member and said first film, said first film having at least oneopening therein; a patch sealed to said first film such that said patchcovers said at least one opening in said first film, said patch having agas transmission rate of at least about 50,000 cc/m²/24 hrs./atm. at 73°F.; and a second, substantially gas-impermeable film that encloses saidpatch, whereby, removal of said second, substantially gas-impermeablefilm allows for a flow of gases through said patch and said at least oneopening, into and out of the package.
 2. A package as set forth in claim1, wherein said at least one opening comprises a hole in said firstfilm.
 3. A package as set forth in claim 1, wherein said at least oneopening comprises a series of perforations or slits in said first film.4. A package as set forth in claim 1, wherein said patch comprises amicroporous material.
 5. A package as set forth in claim 1, wherein saidsecond film is sealed directly to said first film.
 6. A package as setforth in claim 1, wherein said first film comprises at least onematerial selected from ethylene vinyl alcohol copolymer, vinylidenechloride copolymer, nylon and polyester.
 7. A package as set forth inclaim 1, wherein said second film comprises at least one materialselected from ethylene vinyl alcohol copolymer, vinylidene chloridecopolymer, nylon and polyester.
 8. A package as set forth in claim 4,wherein said microporous material comprises spun-bonded polyolefin orspun-bonded polyester.
 9. A web, comprising: a first, substantiallygas-impermeable film having at least one opening therein; a patch sealedto said first film such that said patch covers said at least one openingin said first film, said patch having a gas transmission rate of atleast about 50,000 cc/m²/24 hrs./atm. at 73° F.; and a second,substantially gas-impermeable film that encloses said patch and issealed to said first film, whereby, removal of said second,substantially gas-impermeable film allows for a flow of gases throughsaid patch and said at least one opening.
 10. A web as set forth inclaim 9, wherein said at least one opening comprises a hole in saidfirst film.
 11. A web as set forth in claim 9, wherein said at least oneopening comprises a series of perforations or slits in said first film.12. A web as set forth in claim 9, wherein said patch comprises amicroporous material.
 13. A web as set forth in claim 9, wherein saidfirst film comprises at least one material selected from ethylene vinylalcohol copolymer, vinylidene chloride copolymer, nylon and polyester.14. A web as set forth in claim 9, wherein said second film comprises atleast one material selected from ethylene vinyl alcohol copolymer,vinylidene chloride copolymer, nylon and polyester.
 15. A web as setforth in claim 12, wherein said microporous material comprisesspun-bonded polyolefin or spun-bonded polyester.